pythagorean theorem
TRANSCRIPT
The Pythagorean Theorem
Presented by: Tanya Van DamKalles Junior High
Algebra 2Spring 2000
Pythagoras• Lived in southern
Italy during the sixth century B.C.
• Considered the first true mathematician
• Used mathematics as a means to understand the natural world
• First to teach that the earth was a sphere that revolves around the sun
Right Triangles• Longest side is the
hypotenuse, side c (opposite the 90o angle)
• The other two sides are the legs, sides a and b
• Pythagoras developed a formula for finding the length of the sides of any right triangle
The Pythagorean Theorem
“For any right triangle, the sum of the areas of the two small squares is equal to the area of the larger.”
aa22 + b + b22 = c = c22
Proof
Applications• The Pythagorean theorem has far-reaching
ramifications in other fields (such as the arts), as
well as practical applications.
• The theorem is invaluable when computing
distances between two points, such as in navigation
and land surveying.
• Another important application is in the design of
ramps. Ramp designs for handicap-accessible sites
and for skateboard parks are very much in demand.
Baseball Problem
A baseball “diamond” is really a square.
You can use the Pythagorean theorem to find distances around a baseball diamond.
Baseball Problem
The distance between consecutive bases is 90feet. How far does a catcher have to throwthe ball from home plate to second base?
Baseball Problem
To use the Pythagorean theorem to solve for x, find the right angle.
Which side is the hypotenuse?
Which sides are the legs?
Now use: aa22 + b + b22 = c = c22
Baseball ProblemSolution
• The hypotenuse is the distance from home to second, or side x in the picture.
• The legs are from home to first and from first to second.
• Solution: x2 = 902 + 902 =
16,200 x = 127.28 ft
Ladder Problem
A ladder leans against a second-story window of a house. If the ladder is 25 meters long, and the base of the ladder is 7 meters from the house, how high is the window?
Ladder ProblemSolution
• First draw a diagram that shows the sides of the right triangle.
• Label the sides: – Ladder is 25 m– Distance from
house is 7 m
• Use a2 + b2 = c2 to solve for the missing side. Distance from house: 7 meters
Ladder ProblemSolution
72 + b2 = 252
49 + b2 = 625 b2 = 576 b = 24 m
How did you do? A = 7 m
Sources Great info on the Pythagorean theorem,
Pythagoras, and other math-related topics:
– The Baseball Problem
– Pythagoras of Samos
– Pythagoras Playground
– Microsoft Encarta 2000